H8SX1663 datasheet(233/1158 Pages) RENESAS

233 / 1158 page

Section 6 Bus Controller (BSC)

Rev.1.00 Jun. 07, 2006 Page 181 of 1102

REJ09B0294-0100

(4) Number of Access Cycles

(a) Basic Bus Interface

The number of access cycles in the basic bus interface can be specified as two or three cycles by

the ASTCR. An area specified as 2-state access is specified as 2-state access space; an area

specified as 3-state access is specified as 3-state access space.

For the 2-state access space, a wait cycle insertion is disabled. For the 3-state access space, a

program wait (0 to 7 cycles) specified by WTCRA and WTCRB or an external wait by

WAIT can

be inserted.

Number of access cycles in the basic bus interface

= number of basic cycles (2, 3) + number of program wait cycles (0 to 7)

+ number of

CS extension cycles (0, 1, 2)

[+ number of external wait cycles by the

WAIT pin]

Assertion period of the chip select signal can be extended by CSACR.

(b) Byte Control SRAM Interface

The number of access cycles in the byte control SRAM interface is the same as that in the basic

bus interface.

Number of access cycles in byte control SRAM interface

= number of basic cycles (2, 3) + number of program wait cycles (0 to 7)

+ number of

CS extension cycles (0, 1, 2)

[+ number of external wait cycles by the

WAIT pin]

(c)

Burst ROM Interface

The number of access cycles at full access in the burst ROM interface is the same as that in the

basic bus interface. The number of access cycles in the burst access can be specified as one to

eight cycles by the BSTS bit in BROMCR.

Number of access cycles in the burst ROM interface

= number of basic cycles (2, 3) + number of program wait cycles (0 to 7)

+ number of

CS extension cycles (0, 1)

[+number of external wait cycles by the

WAIT pin]

+ number of burst access cycles (1 to 8)

× number of burst accesses (0 to 63)

H8SX1663 bảng dữ liệu(PDF) 233 Page - Renesas Technology Corp